Australia said on Friday just one asylum-seeker boat has been intercepted over the past week, marking a sharp reduction under the government’s hardline policy, while eight alleged people-smugglers were arrested in Indonesia.

Prime Minister Tony Abbott’s vow to “Stop the Boats” was a centrepiece of his recent election campaign and Immigration Minister Scott Morrison said the policies were working.

Under Operation Sovereign Borders, 215 people had been intercepted in the last three weeks, significantly down on the thousands who were routinely arriving each month earlier this year.

“The experience of people confronting our policies and our resolve is what makes the difference,” Morrison said in a weekly briefing.

The policies include turning back people-smuggling boats to Indonesia and plans to pre-emptively buy up rickety fishing vessels and pay villagers for intelligence.

The government has also maintained the policies of the old Labor administration in which all asylum-seekers arriving by boat are sent to Papua New Guinea or Nauru in the Pacific for processing and resettlement.

Morrison refused to say if any boats had been towed back to Indonesia, their usual point of departure.

“The practice in these briefings is not to comment on operations that might jeopardise current or future operations, so I won’t be commenting on those matters,” he said.

The government has come under fire for not providing the public with more timely details on boat arrivals or tow backs, but Abbott denied trying to prevent any bad publicity.

“Our job is to stop the boats. It’s not to provide sport. It’s not to provide copy. It’s not to start an argument,” he said.

“The job of the government is to get things done and what we want to get done as quickly as we humanly can is this urgent national imperative of stopping the boats.”

At the same briefing, Australian Federal Police Commissioner Tony Negus said co-operation with Indonesia had resulted in 17 people-smuggling attempts being halted since September 8, preventing more than 500 suspected asylum-seekers from making boat journeys.

He added that Indonesian police had recently made eight arrests, including three “high-value targets” involved in organising operations.

“Importantly, three high-value targets – these are people who are facilitators and organisers within Indonesia who put people on those boats,” he said.

“They’ll be charged with organising multiple ventures to Australia.”

Indonesian police were also seeking an arrest warrant for a suspected people-smuggling kingpin, he added, without going into further details.

“We’re confident we have a good lead on this individual,” said Negus, who has just returned from high-level talks in Jakarta.

Meanwhile, a High Court on Friday upheld the government’s power to impose mandatory prison terms for convicted people-smugglers.

The case was brought by a crew member of a boat which ferried 52 asylum-seekers to Australia in 2010 with Bonan Darius Magaming appealing his five-year jail term, the mandatory minimum sentence.

But the court, by a majority, ruled the mandatory sentencing provision in the Migration Act was lawful, a move welcomed by Morrison.

“If people seek to break those laws then they can expect to suffer the consequences of those penalties,” he told reporters.